A hormone called progesterone helps reduce how frequently and how severely women experience hot flashes and night sweats after menopause somewhat, according to a new study.
Progesterone capsules might offer an alternative therapy to women who don't want to be on an estrogen-based treatment, said the lead author of the study, Christine Hitchcock.
"There are certainly some people for whom estrogen is not an appropriate therapy and other people who wish to avoid it for other reasons. And progesterone offers a choice," Hitchcock, a researcher at the University of British Columbia, told Reuters Health.
Estrogen had been a popular hormone therapy to treat menopausal symptoms until some large studies raised concerns about a possible increased risk of stroke and cancer among women who were taking it (see Reuters Health reports of October 19, 2010 and January 31, 2011).
Progesterone has been used in hormone replacement therapy to treat menopausal symptoms, but it is typically thought of as an add-on to estrogen therapy to help protect the uterus from abnormal thickening. It is approved by the Food and Drug Administration to for that use, and for abnormal menstrual bleeding symptoms.
A few studies have looked at whether progesterone alone can also help relieve menopausal symptoms, such as hot flashes (also called hot flushes), but the findings have not been very promising.
"The view is that progesterone has no effect on hot flushes," said Dr. John Studd, a professor of gynecology at Imperial College London who has studied progesterone and menopausal symptoms.
But Hitchcock said some physicians have seen benefits among their patients who were taking progesterone.
More benefit from hormones
To get a better idea of whether it actually has an impact on menopausal symptoms, she and her colleagues gave 68 women three 100-mg pills of progesterone each evening for 12 weeks. Such pills cost about $1 each.
They compared the number and severity of night sweats and hot flashes among these women to 46 similar women who took a placebo instead.
For four weeks before taking the pills and during the three months of the study, the women recorded their symptoms.
The women who took progesterone started out experiencing an average of seven night sweats or hot flashes a day.
At the end of the study they reported having three fewer episodes daily.
In comparison, women taking the fake pills went from a little more than six episodes a day down to about four - a benefit half the size seen in the hormone group.
Similarly, on a scale from one to four, women on the hormone pills reported their symptoms to be 0.6 points less severe at the end of the study than at the beginning - down to 2.0 from 2.6.
In comparison, the placebo group reported their symptoms to be 0.4 points less severe at the end of the study - starting out at 2.4 and ending up at 2.0 on the severity scale.
How does progesterone work?
Hitchcock said "it's a bit of a mystery" as to how progesterone might be helping to ease women's symptoms.
One way might be to widen the temperature range at which the body feels comfortable.
Studd, who was not involved in this study, pointed out that progesterone acts as a tranquilizer, which is why the women in the study were given the hormone before bed.
"It will help sleep...and therefore they can sleep through their hot flushes and sweats," he told Reuters Health.
Hitchcock's group teased out daytime and nighttime symptoms, and found that women had about one fewer daytime hot flash after the hormone treatment compared with the placebo.
The researchers wrote in their study, published in the journal Menopause, that the results indicate "that the benefit of progesterone was not caused by improved sleep masking night sweats."
Still, improving sleep is an important gain for women whose symptoms can disrupt sleep, Hitchcock said.
Studd said the risks to taking progesterone is that women who experienced pre-menstrual irritability or depression in their younger years are at risk of triggering those symptoms while they're on the hormone.
Two of the women who took progesterone in the study reported feeling depressed during the trial.
"The vast majority of people said that they had nothing (adverse) that they noticed," Hitchcock said. She added that the study was not designed to evaluate the long term safety of the drug.
Her study was funded by donations from individuals and the hormone was donated by the company that makes it.
Studd, who is a proponent of estrogen-based hormone replacement therapy, remains skeptical that progesterone alone can relieve menopausal symptoms.